package com.hmdp.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.entity.Shop;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.hmdp.utils.RedisConstants.*;

@Slf4j
@Component
public class CacheClient {
    private StringRedisTemplate stringRedisTemplate;
    private static final ExecutorService CACHE_REBUILD_EXECUTOR= Executors.newFixedThreadPool(10);

    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }
    
    public void set(String key, Object value, Long time, TimeUnit unit){
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value),time,unit);
    }


    public void saveShopToRedis(String key,Object value, Long time, TimeUnit unit) throws InterruptedException {
        Thread.sleep(200);
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));

        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(redisData));
    }



    private <R,ID> R queryWithPassThrough(
            String keyPrefix, ID id, Class<R> type, Function<ID,R> dbCallback,Long time,TimeUnit unit){
        String key=keyPrefix+id;

        String json=stringRedisTemplate.opsForValue().get(key);

        if(StrUtil.isNotBlank(json)){
            return JSONUtil.toBean(json,type);
        }

        if(json!=null){
            return null;
        }

        R r=dbCallback.apply(id);

        if(r==null){
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        
        this.set(key,r,time,unit);
        
        return r;
    }

    private <R,ID> R queryWithMutex(
            String keyPrefix,ID id,Class<R> type,Function<ID,R> dbCallback,Long time,TimeUnit unit){
        String key=keyPrefix+id;

        String json = stringRedisTemplate.opsForValue().get(key);

        if(StrUtil.isNotBlank(json)){
            return JSONUtil.toBean(json, type);
        }

        if(json!=null){
            return null;
        }

        String lockKey=LOCK_SHOP_KEY+id;
        
        R r= null;

        try {
            boolean isLock=getLock(lockKey);

            if(!isLock){
                Thread.sleep(50);
                return queryWithMutex(keyPrefix, id, type, dbCallback, time, unit);
            }

            json = stringRedisTemplate.opsForValue().get(key);

            if(StrUtil.isNotBlank(json)){
                return JSONUtil.toBean(json, type);
            }

            r = dbCallback.apply(id);
            if(r==null){
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
                return null;
            }

            this.set(key, r, time, unit);

        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            unlock(lockKey);
        }


        return r;
    }


    public <R,ID> R queryWithLogicalExpire(
            String keyPrefix, ID id, Class<R> type, Function<ID,R> dbCallback,Long time,TimeUnit unit){
        String key=keyPrefix+id;

        String json = stringRedisTemplate.opsForValue().get(key);

        // 如果缓存不存在
        if(StrUtil.isBlank(json)){
            return null;
        }

        RedisData redisData = JSONUtil.toBean(json, RedisData.class);

        R r=JSONUtil.toBean((JSONObject) redisData.getData(),type);

        LocalDateTime expireTime = redisData.getExpireTime();

        // 没有过期
        if(expireTime.isAfter(LocalDateTime.now())){
            return r;
        }

        String lockKey=LOCK_SHOP_KEY+id;
        boolean isLock=getLock(lockKey);

        if(isLock){
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    R newR = dbCallback.apply(id);
                    this.saveShopToRedis(key,newR,time,unit);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                    unlock(lockKey);
                }
            });
        }

        if(StrUtil.isBlank(json)){
            return null;
        }

        // 没有过期
        if(expireTime.isAfter(LocalDateTime.now())){
            return r;
        }

        return r;


    }


    private boolean getLock(String key){
        Boolean flag=stringRedisTemplate.opsForValue().setIfAbsent(key, "1",10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }



}
